1. Field of the Invention
The subject matter of this invention relates generally to fuses and particularly to arrangements for terminating the ends of fuse ribbons.
2. Description of the Prior Art
High voltage current limiting fuses utilizing radially oriented elements or ribbons with current limiting notches and/or zig-zag (i.e. pleated) arrangements are known. Examples may be found in the following U.S. Pat. No. 2,866,040 issued Dec. 23, 1968 to W. F. Skeats; U.S. Pat. No. 3,134,874 issued May 26, 1964 to F. L. Cameron and assigned to the assignee of the present invention; U.S. Pat. No. 3,319,029 issued May 9, 1967 to P. C. Jacobs, Jr.; U.S. Pat. No. 2,773,151 issued Dec. 4, 1956 to E. W. Sugden; and U.S. Pat. No. 3,624,580 issued Nov. 30, 1971 to W. J. Elliott. Generally in all of the aforementioned patents the termination of the fuse element is made by soldering the element of similarly fastening it to a transverse spacer or support near the end of the fuse barrel. It would be convenient if radially the fuse element could be terminated by extending it over the edge of the support spacer and along the side of the fuse barrel to be compressed between the fuse barrel and one of the fuse ferrules. This is accomplished with circumferentially oriented fuse elements by a method known as magneforming. The magneforming process is described in U.S. Pat. No. 3,333,336 issued Aug. 1, 1967 to F. L. Cameron et al and assigned to the assignee of the present invention. Circumferentially oriented fuse elements are shown in the following U.S. Pat. No. 3,636,491 issued Jan. 18, 1972 to F. L. Cameron and assigned to the assignee of the present invention; U.S. Pat. No. 3,153,713 issued Oct. 20, 1964 to T. F. Brandt, Jr.; and U.S. Pat. No. 3,394,333 issued July 23, 1968 to P. C. Jacobs, Jr. Although the circumferential arrangement of fuse ribbons within a fuse is more easily adapted for termination by the magneforming or similar process, the circumferential arrangement of fuse elements is less desirable than the radial arrangement of fuse elements in some cases for a number of reasons; First, for a given number of fuse elements, element-to-element spacing within the fuse body is closer for a circumferential arrangement than for a radial arrangement. Close spacing increases the risk of fulgurite merging during the fuse interruption operation. Second, in the case of a cross-sectional analysis of circumferentially oriented fuse elements, it has been found that the arc energy of fusing is concentrated in a relatively narrow annulus. This causes a higher energy input into nearby arc quenching sand per unit volume of sand than is caused by utilizing the same number of radially oriented fuse elements because of the relatively wider annulus. Consequently the use of circumferentially oriented fuse elements rather than radially oriented fuse elements results in a lower interrupting capacity for the fuse. Finally, the radial configuration permits the heat generated during a fusing operation to have access to a greater volume of cooling sand per fuse element. This results in better arc cooling and subsequently permits improved arc extinction which is desirable. It would be advantageous to provide a fuse which had all of the previously described advantages of radially oriented fuse elements and the advantages associated with the circumferentially oriented fuse elements where convenient disposition of the end of the fuse element is made somewhere along the longitudinal body of the fuse barrel to facilitate termination by the magneforming process or a similar process.